﻿using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Dynamic;
using System.Reflection;

namespace MelodysDemo.Application.AppServices
{//转Excel
    public static class ToExcel
    {
        #region 将集合对象转为DataTable

        /// <summary>
        /// 将 List{T} 转换为 DataTable.
        /// </summary>
        public static DataTable ToDataTable<T>(this List<T> list)
        {
            var tb = new DataTable(typeof(T).Name);

            PropertyInfo[] props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);

            foreach (PropertyInfo prop in props)
            {
                Type t = GetCoreType(prop.PropertyType);
                tb.Columns.Add(prop.Name, t);
            }

            foreach (T item in list)
            {
                var values = new object[props.Length];

                for (int i = 0; i < props.Length; i++)
                {
                    values[i] = props[i].GetValue(item, null);
                }

                tb.Rows.Add(values);
            }

            return tb;
        }
        /// <summary>
        /// 将 List{T} 转换为 DataTable.(动态化)
        /// </summary>
        public static DataTable ToDataTableFromExpandoObjects(List<PropertyDescriptor> propertyDescriptors, List<ExpandoObject> dynamicObjects)
        {
            var dataTable = new DataTable();

            // 添加列
            foreach (var propertyDescriptor in propertyDescriptors)
            {
                dataTable.Columns.Add(propertyDescriptor.Name, propertyDescriptor.PropertyType);
            }

            // 添加行
            foreach (var dynamicObject in dynamicObjects)
            {
                var dataRow = dataTable.NewRow();

                foreach (var propertyDescriptor in propertyDescriptors)
                {
                    dataRow[propertyDescriptor.Name] = propertyDescriptor.GetValue(dynamicObject);
                }

                dataTable.Rows.Add(dataRow);
            }

            return dataTable;
        }

        /// <summary>
        /// 指定类型的确定可以为null
        /// </summary>
        public static bool IsNullable(Type t)
        {
            return !t.IsValueType || (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Nullable<>));
        }
        /// <summary>
        /// 如果类型为Nullable，则返回基础类型，否则返回类型
        /// </summary>
        public static Type GetCoreType(Type t)
        {
            if (t != null && IsNullable(t))
            {
                if (!t.IsValueType)
                {
                    return t;
                }
                else
                {
                    return Nullable.GetUnderlyingType(t);
                }
            }
            else
            {
                return t;
            }
        }

        #endregion

        #region 将DataTable数据导入到excel中

        /// <summary>
        /// 将DataTable数据导入到excel中
        /// </summary>
        /// <param name="data">要导出的数据</param>
        /// <param name="sheetName">excel的sheet的名称</param>
        /// <param name="isColumnWritten">DataTable的列名是否要导入</param>
        /// <returns></returns>
        public static byte[] DataTableToExcel(DataTable data, string sheetName, bool isColumnWritten)
        {
            int i = 0;
            int j = 0;
            int count = 0;
            ISheet sheet = null;
            IWorkbook workbook = null;
            MemoryStream fs = null;
            fs = new MemoryStream();
            workbook = new XSSFWorkbook();
            try
            {
                if (workbook != null)
                    sheet = workbook.CreateSheet(sheetName);
                else
                    return null;
                if (isColumnWritten == true) //写入DataTable的列名
                {
                    IRow row = sheet.CreateRow(0);
                    for (j = 0; j < data.Columns.Count; ++j)
                    {
                        row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                    }
                    count = 1;
                }
                else
                {
                    count = 0;
                }

                for (i = 0; i < data.Rows.Count; ++i)
                {
                    IRow row = sheet.CreateRow(count);
                    for (j = 0; j < data.Columns.Count; ++j)
                    {
                        row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                    }
                    ++count;
                }
                workbook.Write(fs); //写入到excel
                return fs.ToArray();
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                return null;
            }
        }
        #endregion

        #region 将excel中的数据导入到DataTable中

        /// <summary>
        /// 将excel中的数据导入到DataTable中
        /// </summary>
        /// <param name="fileName">excel的文件名（完整路径）</param>
        /// <param name="sheetName">excel工作薄sheet的名称</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
        /// <returns>返回的DataTable</returns>
        public static DataTable ExcelToDataTable(string fileName, string sheetName, bool isFirstRowColumn)
        {
            IWorkbook workbook = null;
            ISheet sheet = null;
            FileStream fs = null;
            DataTable data = new DataTable();
            int startRow = 0;
            try
            {
                fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                if (fileName.IndexOf(".xlsx") > 0) // 2007版本
                    workbook = new XSSFWorkbook(fs);
                else if (fileName.IndexOf(".xls") > 0) // 2003版本
                    workbook = new HSSFWorkbook(fs);

                if (sheetName != null)
                {
                    sheet = workbook.GetSheet(sheetName);
                    if (sheet == null) //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
                    {
                        sheet = workbook.GetSheetAt(0);
                    }
                }
                else
                {
                    sheet = workbook.GetSheetAt(0);
                }
                if (sheet != null)
                {
                    IRow firstRow = sheet.GetRow(0);
                    int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数

                    if (isFirstRowColumn)
                    {
                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                        {
                            ICell cell = firstRow.GetCell(i);
                            if (cell != null)
                            {
                                string cellValue = cell.StringCellValue;
                                if (cellValue != null)
                                {
                                    DataColumn column = new DataColumn(cellValue);
                                    data.Columns.Add(column);
                                }
                            }
                        }
                        startRow = sheet.FirstRowNum + 1;
                    }
                    else
                    {
                        startRow = sheet.FirstRowNum;
                    }

                    //最后一列的标号
                    int rowCount = sheet.LastRowNum;
                    for (int i = startRow; i <= rowCount; ++i)
                    {
                        IRow row = sheet.GetRow(i);
                        if (row == null) continue; //没有数据的行默认是null　　　　　　　

                        DataRow dataRow = data.NewRow();
                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                        {
                            if (row.GetCell(j) != null) //同理，没有数据的单元格都默认是null
                                dataRow[j] = row.GetCell(j).ToString();
                        }
                        data.Rows.Add(dataRow); 
                    }
                }
                return data;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                return null;
            }
        }
        #endregion

    }
}
